With the introduction of the innovative new SHIELD™ commercial water heater, Lochinvar Corporation is making waves by proving that sometimes it's what's not inside that really counts. With inputs up to 500,000 Btu/hr, 96 percent thermal efficiency and storage up to 125 gallons, SHIELD has everything it takes to provide the ultimate green operation – without the risk of lime scale buildup inside the tank. With other commercial water heaters, heat transfer takes place inside the tank through flue tubes or coil-type heat exchangers. As a result, thermal efficiency decreases over time due to lime scale buildup, which gradually drives operating costs up. In fact, as little as one-fourth of an inch of lime scale on the heat exchanger can increase operating costs by 25 percent and cause tank failure in as little as two years. Designed to provide a 100 percent effective defense against this problem, SHIELD is equipped with the industry's most advanced stainless steel heat transfer system located outside of the tank, ensuring the same high efficiency and low operating costs throughout its life cycle. For added flexibility, SHIELD offers rooftop or sidewall venting options, including conventional, direct vent and concentric direct vent, all using PVC or CPVC pipe with vent runs up to 100 feet. Ideal for green commercial buildings, SHIELD provides low NOx ratings compatible with the most stringent air quality standards. The NEG/REG sealed combustion system allows the unit to operate with inlet gas pressure as low as four inches of water column and delivers a quiet, environmentally friendly supply of heat. Utilizing a fully modulating burner with 5:1 turndown, SHIELD can fire as low as 20 percent of maximum input when demand is lowest, and increase to 100 percent for peak-demand periods. This results in better overall efficiency and less cycling compared to "on-off" tank-type units that can only fire at full force. In addition, SHIELD is equipped with an advanced water heater control, which makes system setup, service and operation a breeze. The innovative SMART CONTROL™ features a two-line, 16-character backlit LCD display that provides readouts of setup, system status and diagnostic information in words, not codes. SMART CONTROL also includes night setback, time clock, alarm contacts, runtime contacts and manual-reset high limit. The outstanding life cycle efficiency and performance of SHIELD can serve even the highest demand commercial applications through manifolded installation of multiple units. For example, five SHIELD SNA 500 models can provide a total storage of 625 gallons with maximum input of 2.5 million Btu/hr. Another key advantage with SHIELD is that the storage tank features very high drawdown for more usable hot water, faster.